Stimulation frequency-dependent reductions in skeletal muscle force and speed in creatine kinase-deficient mice

A. de Haan, M. Bien, P.W.L. Verdijk

    Research output: Contribution to JournalArticleAcademicpeer-review

    Abstract

    Force and speed parameters were obtained from isometric contractions at different stimulation frequencies of creatine kinase-deficient and wildtype in situ mouse medial gastrocnemius muscles. The absence of creatine kinase did not affect force production at higher stimulation frequencies. However, at frequencies below 140 Hz, forces were lower than the controls (P < 0.05); at the lowest frequency applied (80 Hz) the force was reduced to ≃ 60% compared with the wildtype muscles. In contrast, twitch force was not affected. When the contractions were preceded by a brief tetanus (50 ms), the effects of lacking creatine kinase on force production were more pronounced; at 80 Hz stimulation isometric force was further reduced to 66.5 ± 6.2% (mean ± SD; n = 5) of the single contractions of the deficient muscles and to ≃ 42% of the wildtype muscles. Twitch force was now also reduced (by ≃ 50%) after the tetanus. The speed of the muscles was not affected in the single contractions. However, after a preceding tetanus, the rate of force rise was reduced by ≃ 14% at high frequencies of stimulation. With decreasing frequencies (below 250 Hz), the reduction in speed became more pronounced; at 80 Hz the rate in the creatine kinase-deficient muscles was only 55.2 ± 3.9% (mean ± SD; n = 5) of the wildtype muscles. No effects of the deficiency were found for the half relaxation times. The data suggest that an impaired creatine kinase system leads to lower activation levels at submaximal stimulation frequencies, possibly by a reduction in Ca
    Original languageEnglish
    Pages (from-to)217-222
    Number of pages6
    JournalActa Physiologica Scandinavica
    Volume166
    DOIs
    Publication statusPublished - 1999

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